The Ca2+ release channel mediates rapid Ca2+ release into the cytoplasm from the sarcoplasmic reticulum (SR) during excitation-contraction coupling in skeletal muscle. The channel complex is a homotetramer composed of four subunits of 565,000 Mr each. The channel protein was solubilized with CHAPS and purified to homogeneity from SR membranes of rabbit fast twitch skeletal muscle. Under physiological conditions, the Ca2+ release channel exists in different functional states which are referred to as "closed" and "open". Following on our previous successes in single particle reconstruction, we have carried out studies of the channel under different chemical conditions at which the channel exhibits various electrical properties and ryanodine binding affinities. We have also started to use nanogold reagent bound to ryanodine in order to locate its binding sites.